1. Field of the Invention
The present invention relates to an apparatus for detecting an amount of feed of a sheet member, which can control a sheet feeding means by detecting the amount of feed of the sheet member.
2. Related Background Art
In a conventional recording apparatus used with a printer, facsimile, word processor and the like, an image was recorded on a recording sheet (to be fed) per a predetermined printing width (per one line) by means of a recording head, and the recording sheet was fed by a predetermined amount (corresponding to the printing width) to effect a line space whenever each line was printed; in this way, the printing operations were repeated to obtain the whole image.
In this case, although the accuracy of the amount of feed of the recording sheet differs in dependence upon resolving power of the character, since the resolving power of the character is normally in the order of 200 dot/inch - 400 dot/inch, the accuracy of the amount of feed of the recording sheet was required to have a value of 60-30 .mu.m. In order to obtain such feed accuracy, the diameter and rotational amount of a feed roller were previously calculated in correspondence to the amount of feed of the recording sheet (to be fed by the feeding roller), and the recording sheet was fed by controlling a driving time of a feed motor for driving the feed roller by means of a CPU.
However, in the above-mentioned conventional recording apparatus, in order to maintain such feed accuracy for the feed amount of the recording sheet, the critical or severe control of parts was required. For example, the accuracy regarding the diameter and/or eccentricity of the feed roller must have been maintained within a value less than 10 .mu.m. Further, even when such severe control of the parts was maintained, if the relative slipping movement occurred between the recording sheet and the feed roller, the above-mentioned accuracy of the feed amount of the recording paper could not often be maintained, thus worsening the quality of the recorded image.